In production of semiconductor devices such as microprocessors, logic LSI, DRAM, flush memories and CCD and flat panel display devices such as TFT liquid crystal, pattern formation and thin film formation are carried out at a level of from submicron to nano-meter order on the surface of a substrate of e.g. silicon, silicon oxide or glass, and it has been an extremely important issue to reduce a very small amount of contaminants on the substrate surface in each step in production. Among such contaminants on the substrate surface, particularly particle contaminants, organic contaminants and metal contaminants decrease electric characteristics and yield of devices, and therefore they have to be reduced as far as possible before the next step is carried out. For removal of the contaminants, cleaning of the substrate surface by means of a cleaning solution is commonly carried out.
In recent years, in the production of devices, further improvement in the throughput and the production efficiency is required. Substrates for producing semiconductor devices tend to be increasingly microsized and highly integrated, and a cleaning method is desired which is capable of highly cleaning the substrate surface quickly and which is not only excellent in the ability to remove metal contaminants and particle contaminants but also the ability to prevent reattaching after cleaning.
It is commonly known that for the removal of particle contaminants, cleaning with an alkaline solution is effective. For cleaning the substrate surface for semiconductor devices such as semiconductor elements or display devices, an aqueous alkaline solution such as an aqueous ammonia solution, an aqueous potassium hydroxide solution or an aqueous tetramethylammonium hydroxide solution, is employed. Further, cleaning (so-called “SC-1 cleaning” or “APM cleaning”) with a cleaning agent (so-called “SC-1 cleaning agent” or “APM cleaning agent”) comprising ammonia, hydrogen peroxide and water, is also widely employed (Non-Patent Document 1).
However, in the case of the alkaline cleaning solution, etching of a silicon or silicon oxide film on the substrate surface is worried, and it is difficult to sufficiently remove composite contaminants of an organic matter and a metal.
That is why, in recent years, an acidic solution has been proposed wherein a surfactant is added to an acidic solution which is effective to remove metal contaminants on the substrate surface for the purpose of improving the ability to remove particle contaminants.
For example, it has been proposed to clean a silicon wafer by means of a specific surfactant and hydrofluoric acid (Patent Document 1), to clean a silicon wafer by means of a solution wherein a surfactant and ozone are added in an aqueous hydrofluoric acid solution (Patent Document 2) or to remove metal impurity and particle contaminants attached on a substrate having a metal wiring by means of a cleaning solution wherein an organic acid compound is added to a dispersion and/or a surfactant (Patent Document 3).
However, in the case of a solution containing hydrofluoric acid or its salt, in addition to etching of a coexistent thin layer, disposal of waste liquid containing fluorine ions is problematic. Further, in the case of a cleaning solution wherein an organic acid compound is added to a surfactant, it is difficult to wet a substrate surface made of a low dielectric constant (Low-k) material having a strong hydrophobicity, and the ability to remove contaminants on the substrate surface is insufficient.    Patent Document 1: JP-A-7-216392    Patent Document 2: JP-A-8-69990    Patent Document 3: JP-A-2001-7071    Non-Patent Document 1: W. Kern and K. A. Puotinen: RCA Review, p. 187, June (1970)